Below are the pictures I took of my Samsung D3 Station (HX-D301TDB) 3TB USB 3.0 external hard drive.
I opened the enclosure and took out the hard drive to use it as an internal drive.
Inside was a Seagate ST3000DM001-1E6166 (Barracuda 7200.14 series) desktop drive.

Disassembling this particular enclosure is not that difficult. You do need to work carefully to avoid breaking
the notches but it comes apart quite easily. I opened mine without any damage or dent to the enclosure. If my
drive ever fails within the warranty period I will be able to put it back inside the enclosure and nobody will
ever know I had it opened.

There are only two small screws that hold the plastic side panel on. The two screws are hidden behind two foot pads
(see picture). Remove the two pads with a small screwdriver. They should unstick easily and remain intact. After
you remove the screws I recommend you use something like an old credit card to wiggle the thing open. Don't use
anything hard like a metal screwdriver because you may cause dents in the edge of the plastic case and that will
make it obvious you were trying to open it. I used my finger nails on the middle of the plastic panel to make a
small 1 mm gap just so I could insert the credit card between the case and the plastic panel (picture 18 shows
where I started). Then I slowly pushed the credit card along the gap to unclip the notches (see pictures). The
notches are on the panel so try to push the bottom side (where the pads are) outward and the side panel edge
inward. The notches on the side panel are not placed symmetrically along the side so I recommend you work your
credit card from left (where you started) towards the right and first get the side panel loose on the bottom,
then the right and then the upper side (see pictures 16 and 17). The left side will still remain locked by two
notches. Getting those free is a bit harder but I recommend you try to work those with only your hands by slowly
pulling and twisting carefully. Using a credit card or any kind of a tool there could damage the edges of the
plastic ever so slightly, making it obvious the enclosure was tampered with. Just grab the already loose panel
and pull it away from the edge it is clipped to. It should un-clip without too much of a problem.

After you get the side panel off the enclosure you can simply pick up the drive inside and wiggle it out. It is
not screwed down. It is only held in place by four rubber bushings. You just need to take a little care with the
PCB controller board that is attached to the drive and the LED cable that is connected to it. The PCB board of
the enclosure is screwed onto the drive with two screws which you have to remove.

That's all there is to it. You could probably use the enclosure with another drive but I didn't do that myself.
I just put the enclosure in a box and stored it. I don't want to mess with it so I don't damage it. I need to
keep it safe in case I ever need to put the drive back in and take it in for warranty. After 3 years when the
drive warranty expires I may decide to put another drive in.